1. Field of the Invention
The present invention relates to a quartz crystal oscillator device in which a quartz crystal resonator is hermetically sealed in a metallic container, and more particularly to a small quartz crystal oscillator device which is superior in shock resistance and whose resonance frequency is not affected by sealing stress.
2. Prior Art
A conventional support construction of a quartz crystal resonator which is hermetically sealed in a metallic container is shown in FIG. 1. With this construction, a quartz crystal resonator 14 is installed and supported on rigid pins 13, 13 which are electrically connected to external leads 12 of a metallic base 11.
When the quartz crystal resonator 14 is hermetically sealed by cold-welding a metallic cap 15 on the base 11 on which the quartz crystal resonator 14 is supported, however, a distortion stress is caused at the base 11 if the base 11 and the cap 15 are not flat, because the welding mold of a welding machine pushes the flange sections 111 of the base 11 and the cap 15. As a result, the stress is applied to the quartz crystal resonator 14 via a substrate 16 and the pins 13, 13, and the resonance frequency of the quartz crystal resonator is greatly reduced. In addition, when a thin quartz crystal resonator is used to meet the needs for miniaturization of the quartz crystal resonator 14, a strain is caused between the metallic base 11 and the substrate 16 made of ceramics for example due to the difference between the thermal expansion coefficients of the two materials. Thus, a bending stress is applied to the quartz crystal resonator and the temperature and thermal shock characteristics of the quartz crystal resonator are adversely affected. To solve these problems, a method of using coil springs (see FIG. 2) instead of using the rigid pins has been proposed so that the coil springs function to support the quartz crystal resonator and to release the stress applied to the quartz crystal resonator (Japanese Patent Provisional Publication No. 59-5715).
According to FIG. 2, a quartz crystal resonator 23 is installed at the opening of a second coil spring 223 of a support member 22 using conductive adhesive and hermetically sealed by a metallic cap 24 to form a quartz crystal oscillator device 21.
The support member 22 is composed of a first coil spring 221 which is wound on an inner lead 25 connected to an external lead 26, a horizontal section 222 which horizontally extends from the first coil spring 221 and the second coil spring 223 which rises from the end of the horizontal section. This construction is effective in elastically absorbing the above-mentioned sealing stress or external shocks applied to the quartz crystal resonator using the coil springs 221 and 223 and the horizontal section 222. However, the support member 22 is elastic and springy since it includes the coil springs 221 and 223 and the horizontal section 222. Thus, when many support members 22 are selectedly fed by a parts feeder in an assembly process, they are easily tangled with one another at their coil springs 221 and 223, stopping smooth feeding at the parts feeder.
Furthermore, when the support members are mounted by a chip mounting machine, they may not be separated individualy because they are tangled with one another. Thus, the mounting machine is likely to mount two pieces of the support members at the same time or does not properly pick up the support members by suction, thereby preventing proper mounting. Therefore, the support member is not suited for automatic mounting and thus its assembly cost is rather high.